\section{}
\subsection{}
\begin{displaymath}
\begin{array}{|c|c|c|c|c|}
\hline
   A
 & B
 & A\land{}B
 & (\lnot{}A\lor{}\lnot{}B)
 & \lnot{}(\lnot{}A\lor{}\lnot{}B) \\
\hline
\hline
0 & 0 & 0 & 1 & 0 \\
0 & 1 & 0 & 1 & 0 \\
1 & 0 & 0 & 1 & 0 \\
1 & 1 & 1 & 0 & 1 \\
\hline
\end{array}
\end{displaymath}
\\
\begin{displaymath}
\begin{array}{|c|c|c|c|}
\hline
   A
 & B
 & A\Rightarrow{}B
 & \lnot{}A\lor{}B \\
\hline
\hline
0 & 0 & 1 & 1 \\
0 & 1 & 1 & 1 \\
1 & 0 & 0 & 0 \\
1 & 1 & 1 & 1 \\
\hline
\end{array}
\end{displaymath}
\\
\begin{displaymath}
\begin{array}{|c|c|c|c|}
\hline
   A
 & B
 & A\Leftrightarrow{}B
 & \lnot{}(\lnot{}A\lor{}\lnot{}B)\lor{}\lnot{}(A\lor{}B) \\
\hline
\hline
0 & 0 & 1 & 1 \\
0 & 1 & 0 & 0 \\
1 & 0 & 0 & 0 \\
1 & 1 & 1 & 1 \\
\hline
\end{array}
\end{displaymath}
\\
\subsection{a}
\begin{displaymath}
\begin{array}{|c|c|c|}
\hline
   A
 & B
 & \lnot{}(A\lor{}B) \\
\hline 
\hline
0 & 0 & 1 \\
0 & 1 & 0 \\
1 & 0 & 0 \\
1 & 1 & 0 \\
\hline
\end{array}
\end{displaymath}
\\
\subsection{b}
